Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D307/00—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom
  • C07D307/02—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings
  • C07D307/04—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having no double bonds between ring members or between ring members and non-ring members
  • C07D307/10—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having no double bonds between ring members or between ring members and non-ring members with substituted hydrocarbon radicals attached to ring carbon atoms
  • C07D307/12—Radicals substituted by oxygen atoms

Definitions

• This invention relates to new herbicidal compositions of matter. More specifically, this invention relates to the contro of undesirable plant life with 2-methoxy-3-methyl- 6-chiorobenzoic acid, its anhydride, its amides, its esters, ifalkali metal salts, or its amine salts.
• 2-methoxy-3- r'nethyl--chlorobenzoic acid which has the structure (ilOOH will hereinafter be referred to as compound I.
• This chemical compound and its derivatives as cited above have marked activity as herbicides useful for the control of undesirable plant life.
• Compound I can be prepared readily, for example, by the methylation of 3-methyl-6-chlorosalicylic acid.
• the 3-methyl-6-chlorosalicylic acid is first converted to its alkali metal salt by treatment with an alkali metal salt of a weak acid.
• the alkali metal salt of a 3-methy1-6- chlorosalicylic acid is reacted with a minimum excess of 100% of a methylating agent, such as dimethyl sulfate.
• the methylation reaction mixtures is further treated by refluxing in an aqueous solution of alkali metal hydroxide to hydrolyze the obtained carboxylic acid ester which has been formed during the methylation reaction.
• the cooled reaction mixture is then acidified with a mineral acid, and the solid precipitate filtered off.
• the compound I obtained in this manner is suitable for many herbicidal uses as such, but it can be purified, for example, by crystallization from a suitable solvent.
• the anhydride of compound I is prepared by the removal of one molecule of water from two molecules of compound I as the free acid.
• a strong acylating agent such as pyridine.
• a mixture of dry pyridine and dry benzene is treated with 1 mole of the acid chloride of compound I.
• the slightly exothermic reaction proceeds with the formation of an intermediate pyridinium salt.
• One mole of compound I as the free acid is then added, the precipitate of pyridine hydrochloride is removed, and the anhydride of compound I is isolated by removal of the benzene.
• the acid halide of compound I required in the above and other syntheses is prepared by the reaction of the free acid with a phosphorus trihalide in the conventional manner.
• the treatment of compound I with phosphorus trichloride until the reaction ceases produces the acid chloride of compound I.
• Amine salts of compound I are prepared by the addition of the free acid to various amines.
• Typical amines which can be used to prepare such amine salts are dimethylamine, trimethylamine, triethylamine, d-iethanolamine, triethanolamine, isopropylamine, morpholine, and the like.
• the resulting products are, respectively, the di methylamine, trimethylamine, triethylamine, diethanolamine, triethanolamine, isopropylamine, and morpholine salts of 2-methoxy-3-methyl-6-chlorobenzoic acid.
• Esters of compound I are prepared by the condensation of the acid with various alcohols.
• the condensation of methyl alcohol with compound I gives the desired ester, methyl 2-methoxy-3-methyl-6-chlorobenzoate.
• Other typical alcohols which can be used are propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, amyl, hexl, heptyl, octyl, nonyl, decyl, and the like.
• the products are the corresponding alkyl esters of Z-methoxy- 3-methyl-6-chlorobenzoic acid.
• esters are those in which the esterifying group is an unsubstituted alkyl group which contains from 1 to 10 carbon atoms.
• the condensation of the acid with the alcohol is carried out suitably in an inert solvent such as an aromatic hydrocarbon and in the presence of a few percent by weight of an acid catalyst such as p-toluene sulfonic acid.
• the water which forms during the esterification reaction can be removed continuously in many cases from the reaction mixture by distillation as it forms, and its volume can be measured to determine when the esterification is complete. The ester is then isolated by distillation of the inert solvent.
• Amides of compound I can be prepared conveniently by the reaction of the acid halide of compound I with ammonia or various amines.
• the reaction can be carried out in an inert solvent such as ether or benzene.
• Preferably two moles of the amine are used for each mole of the acid halide employed, since the hydrogen halide released during the reaction is taken up by some of the free amine which remains.
• the simplest amide, 2-methoxy-3-methyl-6-chlorobenzamide can be prepared by the reaction of the acid chloride of compound I with ammonia, either as the free gas or as an aqueous solution. This amide can also be prepared by hydrolysis of the corresponding nitrile.
• Substituted amides are prepared by the reaction of the acid halide of compound I with amines such as any of the primary or secondary amines suggested above for the preparation of the amine salts of compound I.
• amines such as any of the primary or secondary amines suggested above for the preparation of the amine salts of compound I.
• the reaction of the acid chloride of compound I with methylamine, butylamine, decylamine, or diethylamine gives the N-methyl-, N-butyl-, N-decyl-, or N,N-diethyl-2-methoxy-3-methyl- 6-chlorobenzamides respectively.
• more complex amines such as the aromatic amines can be used as the amine reactant to give desirable products which are specifically named as anilides
• preferred amine reactants are alkylamines containing up to 10 carbon atoms.
• the compounds of this invention are formulated with inert carriers to obtain proper concentrations and to facilitate handling.
• these compounds can be formulated into dusts by combining them with such inert substances as talcs or clays.
• the alkali metal salts of compound I are particularly suited to such dust formulations, and dusts containing from 5 to 25 percent by weight of active compound are convenient for use in the field.
• the compounds of this invention are preferably applied as sprays. These can be made as simple solutions by dissolving the compounds in organic solvents such as xylene, kerosene,
• esters of compound I which ordinarily are liquids at room temperature, are particularly suited to formulation by this method.
• the amine salts of compound I often show good solubility in water and can be used directly as aqueous solutions.
• the compounds of this invention can also be emulsified or suspended in water by the addition of emulsifiers and wetting agents.
• the formulations of these active herbicidal compounds are either applied directly to the plants to be controlled, or the soil in which the plants are growing can be treated. Substances such as other pesticides, stabilizers, activators, synergists, spreaders and adhesives can be added to the formulations if desired. There is no significant difference in effect from the amount of water or organic solvent for diluting these herbicides, providing the same amount of chemical is distributed evenly over a given area. Such distribution can be obtained, for example, with low-pressure, low-volume sprays at the rate of about 10 gallons of spray per acre.
• the effectiveness of the compounds of this invention in small quantities makes them economically sound for weed control on large areas, with a great saving in labor and cost, in addition to corresponding crop increases.
• These compounds are particularly valuable in weed control because they are harmful to many weeds but harmless or relatively harmless to some cultivated crops. Minute quantities in contact with plant tissues may be absorbed and translocated to all parts of the plant, causing striking changes in the form and functions and often resulting in their death.
• the actual amount of compound to be used depends on a variety of factors but is influenced primarily by the species of undesirable plant to be controlled.
• the solution was filtered and acidified with an excess of hydrochloric acid.
• the precipitate was collectt-lii. washed with water, and dried.
• a yield in the order of 50 g. of product was obtained having a melting point of l07ll4 C.
• the product after recrystallization from benzene-hexane, had a melting point of 118-419 C.
• EXAMPLE 8 Preparation of the Ethyl Ester of Compound I
• Compound I 0.5 mole
• ethyl alcohol 23 g.; 0.5 mole
• 3.0 g. of p-toluenesulfonic acid are dissolved in 500 ml. of benzene, and the solution is placed in a 1 liter, round-bottomed flask fitted with a reflux condenser and a calibrated Dean-Stark tube.
• the solution is heated at reflux temperature until 9 cc. of water have been collected in the Dean-Stark tube.
• the cooled reaction mixture is then extracted twice with 50-cc. portions of 10% sodium carbonate solution, and filtered.
• the benzene is distilled olf in vacuo on the steam bath, and the residue is then distilled in vacuo to give the desired ethyl ester of compound I.
• EXAMPLE 12 Preparation of the Amide of Compound I
• One mole of the acid chloride of compound I is placed with 500 cc. of dry benzene in a l-liter, 3-necked flask fitted with a reflux condenser, mechanical stirrer, and a gas inlet tube having a sparger tip. The mixture is stirred While dry ammonia gas is passed into the mixture for several hours. When the ammonia gas is no longer taken up, the precipitated salt is filtered oil and extracted twice with 100 m1. portions of ether. The ether extracts and benzene filtrate are dried over magnesium sulfate and filtered, and the solvents are distilled off to give the desired amide of compound I.
• EXAMPLE 16 Preparation of an Emulsifiable Concentrate of Comound l
• the fol-lowing concentrate is prepared by mixing the ingredients intimately in the given percentage proportions by weight:
• Percent Compound I 25 Antarox A-400 40 Methanol 35 Antarox A-400 is the trade name under which a nonionic detergent of the aromatic polyethylene glycol ether type is sold. The above concentrate is diluted with water to the desired concentration for use.
• Triton X-100 Percent n Butyl ester of compound I 59 Xylene 10 Triton X-100 5 Kerosene 26 Triton X-100 is the trade name under which an emulisifier of the alkyl aryl polyether alcohol type is sold. The above concentrate is diluted with water to the desired concentration for use.
• EXAMPLE 18 Preparation of a Dust from the Sodium Salt of Compound I
• the sodium salt of compound I (10% by weight) and talc by weight) are combined and ground to the desired particle size in a mechanical grinder-blender.
• the herbicidal activity of chemical compounds is often demonstrated by the ability of the chemicals to kill or arrest the growth of tomato plants.
• the tomato plant is readily grown and maintained under uniform conditions for experimental purposes in greenhouses and its response to chemicals is very similar to that observed for a wide variety of economically important species of undesirable plant life in the field.
• the herbicidal activity of the compounds of this invention can be demonstrated in greenhouse experiments on young potted tomato plants (Bonny Best variety).
• the compounds are formulated into 10 percent wettable powders and are dispersed in water at a concentration of 2,000 parts per million actual chemi- 7 cal.
• Ten milliliters of an aliquot portion of the dispersion is added to the soil surface of the tomato plants, approximately to 7 inches tall.
• 5 holes the size of a pencil and about 1 inch deep are punched in the soil surface around the shoot, and the ten milliliter application is divided equally among the 5 holes. Three plants are used for each application.
• the treated plants are held under greenhouse conditions for 7 days, provided with subterranean watering, and observed for response to treatment.
• the results indicate a high order of herbicidal toxicity of the compounds of this invention.
• Tests carried out on such actual weed species as French weed, pigweed, crabgrass, yellow foxtail, ryegrass, chickweed and white cockle also indicate the marked herbicidal activity of these new compounds.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Agricultural Chemicals And Associated Chemicals (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Priority Applications (5)

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Publications (1)

Family

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Family Applications (1)

Country Status (4)

Cited By (2)

Citations (3)

• 1961
  • 1961-11-08 US US150874A patent/US3130206A/en not_active Expired - Lifetime
• 1964
  • 1964-02-07 GB GB5212/64A patent/GB1001959A/en not_active Expired
  • 1964-02-28 BE BE644542A patent/BE644542A/xx unknown
  • 1964-02-28 NL NL6402014A patent/NL6402014A/xx unknown

Patent Citations (3)

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